1. Field of the Invention
The present invention relates to certain electrically conducting polypyrroles.
2. Prior Art
Most of the known organic polymers are substantially electrically insulating, having conductivities at room temperature on the order of from about 10.sup.-10 ohm.sup.-1. cm.sup.-1 to about 10.sup.-18 ohm.sup.-1.cm.sup.-1. The desire for low-density, flexible, processible conductors generated considerable research for ways to improve the conductivity of known polymers or for new polymers having higher conductivities. Recently, new polymer systems, e.g., poly-p-phenylene, polypyrrole, polyaniline, poly-p-phenylene sulfide, poly(2,5-thienylene), fluoroaluminum, fluorogallium phthalocyanine, all having enhanced electrical conduction properties, have been designed.
Polypyrrole, a thermally stable polymer capable of being doped without using hazardous reagents is among the most desirable of these systems in that it may be prepared electrochemically [Dall'Olio et al V Compt. Pend. C 267, 433 (1968); Diaz et al, J. Chem. Soc. Chem. Commun. 635 (1979)]. This is advantageous in that the properties of the electrochemically prepared film may be altered by merely controllably varying the electrolysis conditions, i.e., nature of the electrolyte or solvent, current density, electrode potential, etc. Although the electrochemical polymerization results in the formation of the polymer in the oxidized or conducting form, the film can be prepared for removal in either the conducting or insulating form.
The electrochemical polymerization method also enables the production of derivatized polypyrroles by polymerizing substituted polypyrroles [Diaz et al, Ext. Linear Chain Compd., 1983, 3, 417-441, Ed. Miller et al, N.Y., N.Y.; Street et al (IBM Res. Lab., San Jose, CA.), Office of Naval Research, Technical Report No. 13, 4/7/83, pp. 1-17; Fleiderman et al, Khim, Geterotsikl. Soedin, 1973, (8), 1146 (Russ.) (C.A. 79: 126202s); Fleiderman et al, Zh. Obsheh, Khim. 1975, 45(i), 197-20 (Russ.) (C.A. 82: 170565y); Diaz Chem. SCR 1981, 17 (1-5), 145-8 (C.A. 95: 194383g); Salmon et al, ACS Symp. Ser. 1982, 65-70 (C.A. 97: 92932j); Diaz et al, J. Electroanal. Chem. Interfacial Electrochem. 1982, 33(2), 233-9 (C.A. 96: 181943k); Diaz et al, J. Electroanal. Chem. Interfacial Electrochem., 1981, 129 (1-2), 115-32 (C.A. 96: 42996s); Kanazauva et al, J. Chem. Soc. Chem. Commun. 1979, (19), 854-5 (C.A. 92: 11403 C)]. Among the polypyrrole derivatives prepared to date are poly-N-alkylpyrroles, poly-N-phenylpyrroles, poly-N-(p-tolyl)pyrroles, poly-N-methylpyrrole-pyrrole copolymers, poly-3,4-dimethylpyrrole, poly-3,4-diphenylpyrrole and poly-3-methylpyrrole.
The beta-substituted (i.e., 3 and/or 4-substituted) polypyrroles are particularly advantageous in that substitution in the 3- and/or 4-position(s) results in increased chain order in that the beta-substituents ensure exclusively alpha-alpha linkages between the pyrrole rings of the polymer.
It is an object of the present invention to provide certain novel electrically conducting 3,4-disubstituted polypyrroles having unexpected advantageous properties and coating compositions containing the polypyrroles as well as substrates coated therewith.